Asthma is definitely genetically predisposed to children. We know that if one parent has asthma, there is a significantly increased risk of having children that are asthmatic. If two parents are asthmatic, then there is an even greater chance their child will have asthma. However, there is a difference between asthma and other genetic conditions, because genetics don't have a direct linear effect on inheritance. Factors such as allergies, obesity and physical activity come into play as well.
Genetics and asthma
There more than 21 different genes that affect whether or not someone will have asthma, and a number of these genes have to be put into motion before a condition like asthma is diagnosed or actually predisposed to someone to be diagnosed. So while it is a genetically predisposed condition, asthma is not the same kind of linear-inherited condition that someone might experience such as the color of their eyes or the color of their skin. Another confirmation that asthma is inherited comes from studies of twins. If one identical twin has asthma, the other twin (who shares all the same genetic information as his/her identical twin) is more likely to have asthma than in the case of non-identical or fraternal twins. Like many other diseases, asthma likely results in part from a tendency present in one's genes and in part from exposures that one encounters in the world around us. Thus, developing asthma is part heredity, part environmental.
Active research, including some being conducted at the Brigham and Women's Hospital, is attempting to identify the specific genes responsible for the inherited tendency toward developing asthma. It is likely that within the next decade we will know at least some of the genetic pieces to the puzzle of what causes asthma. On the other hand, certain studies show that previous studies overestimate the heredity of asthma. This could be because those estimates are based on correlations between family members that share environment as well as genes, which could inflate the development of the condition. Gene-environment interactions are not considered in these large-scale association studies, and we know that these are particularly important in establishing individual risks for asthma. It was assumed that there would be rare mutations that largely impact the development of asthma, more than the common variants we have been studying. But surprisingly, it was found that low frequency mutations explain only a very small amount of asthma risk.
Pregnancy and asthma
When a pregnant woman smokes tobacco, a number of dangerous side effects can be passed on to the unborn child. Asthma is one them. A baby whose mother smokes tobacco during pregnancy has a higher risk of developing the disease while in the womb, and it becomes full-blown asthma during birth. Pregnant women with asthma have also been advised not to panic after new research linked the breathing condition to a much greater risk of health problems in the baby and woman.
Asthmatic mothers-to-be are at "significantly increased" risk of developing dangerously high blood pressure or their child being born prematurely as a result of their breathing difficulty. If a child develops asthma from family history, the best thing a parent can do is to avoid exposing the child to possible triggers.
If you are worried about your child having asthma, speak with your doctor about the precautions you can take.